Monday, July 6, 2009

Unintended benefits

A little while ago, I was reading an AP opinion piece in the newspaper, titled Disease prevention often costs more than it saves. I was skeptical about its premise, but then I read the article, and the details bothered me more. The example used is that of relying on a personal trainer/lifestyle coach to prevent diabetes.

It's a terribly poor example, and whoever Carla Johnson is, I am sad to report that she appears to be neither a mathematician nor a health expert. True, the annual cost of diabetes is about $4100 initially (ref - note, however, that it rises over time) and we are, hypothetically, spending $5400 or $6300 a year to prevent it (note: The article says "$5400" but also says that for every person that this sort of treatment works for, it fails six others, and seven times $900 is $6300, not $5400). So on diabetes, we're saving $600-700 or so per person per year with this program, hypothetically, if each year of the program leads eventually to 1/7 of one year free from diabetes for one person.

However, the health benefits of having someone sort out your diet and exercise problems are not limited to not getting diabetes! Diabetes is the big-ticket item, sure. But is it the only thing? Obesity is linked to many other health problems. What the article author should instead be comparing is the cost of the program - which we expect would be discontinued after the first year or so if it were not making a difference - to the average increased cost of being overweight and not exercising, not just diabetes.

And then there's the other side of the question of cost effectiveness: We have not only a significant portion of the costs being repaid in saved diabetes bills, and much (quite possibly all) of the remainder being repaid in other medical bills; we have additional years of healthy productive life, fewer sick days, etc. Direct medical costs are only about half the total price tag of obesity (ref) and so, even hypothetically paying $900 a year indefinitely for personal lifestyle coaching is, on the scale of a national system, a good idea. After all, we're looking at an expected average positive payout at that point.

So the example is quite poorly considered. Is there a valid point to the op-ed piece? Well, yes. An ounce of prevention is not always worth a pound of cure, and it's worth actually checking to see if it is. But a valuable moral of the story is that you have better be very thorough in weighing the costs of everything being prevented. Narrow focus on particular kinds of costs while ignoring others is how we wound up with this system in the first place.

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